- Patients must have either (1) histologic proof of a high-grade astrocytoma reviewed by a POETIC institutional pathologist or (2) a radiological diagnosis via MRI scan of a typical diffuse pontine tumor made by a POETIC institutional neuroradiologist. Patients with a radiological diagnosis via MRI scan of a typical diffuse pontine tumor will be enrolled on the diffuse pontine tumor arm of the study regardless of histology in cases that are biopsied. Note: For collaborating non-POETIC institutions, the reviews may be done by an institutional pathologist/neuroradiologist.